Clutch mechanism for sewing machines



Jan. l0, 1950 E. scHolJ CLUTCH MECHANISM FCR SEWING MACHINES 3Sh'eets-Sheet l Filed Oct. 1, 1946 Jan. 10, 1950 E. scHolJ 2,494,006

CLUTCH MECHANISM FCR SEWING MACHINES Filed Cot. 1, 194e s sheets-sheet 2IEW/MII@ V 4,

`Fan. l0, 1950 E. scHolJ CLUTCH MECHANISM FCR sEwINC MACHINES 3SheetsfSheeb 3 Filed OCT.. l, 1946 wuemlov @w MC1" mm @Fla BARRCL wlrHECCENTRICITY uP RRE/L wm-l accENTmCnTY DowN Patented Jan. 10,3195()CLUTCH MECHANIsMFoR SEWING MACHINES Edgar Schoij, Chicago, Ill.,assigner to Union Special Machine Company, Chicago, Ill.,'a corporationof Illinois Application octeber 1, 1946, serial No.' vomito Theinvention relates to new and useful improvements in a clutch mechanismof the barrel type for imparting intermittent movements to the 'feedingmechanism of a sewing machine.

An object of the invention is to provide an intermittently operatingclutch mechanism of lthe above type wherein the gripping surface fof theclutch barrel is eccentric to its axis of rotation so that theV grippingline between the roller and the clutch block shifts back and forth onthe clutch block for each rotation of the shaft and wherein the grippingface i the clutch block is so shaped that the wedge angle between theclutch barrel and the clutch block remains sub'- stantially constant asthe gripping lines shift. i A further object of the invention is toprovide a clutch mechanism of the above type wherein means is providedfor changing the eccentricity of the clutch barrel so that the area overwhich the grip shifts may be increased or decreased to furtherdistribute the wear and increase the life and efficiency of the clutch.

lThese and other objects will in part be obvious and will in part behereinafter more fully stated.

In the drawings which show the invention as applied to a cup feed typeof sewing machine,

Figure l is a View partly in side elevation with parts broken away toshow some of the inner mechanism and with parts in vertical section,

Figure 2 is a vertical sectional View through a portion of the machineand showing the means whereby access may be had to the clutch mechanismfor varying the eccentricity of the setting of the clutch barrel on theactuated feed shaft,

Figure 3 is a front view of a portion of the housing for the clutchmechanism showing the cap screw removed from the opening and the indiciaon the clutch barrel for indicating the relative amount of eccentricity,

Figure 4 vis an enlarged sectional View through the clutch mechanism,the section being taken on line iof Figure l,

Figure 5 is a section on line 5 5 of Figure 4,

Figure 5 is a sectional View taken on the line 6 5 of Figure 4,

Figure is a sectional View taken on the line 'I-'i of Figure 4,

Figure 8 is a' sectional view on the line 8--8 of Figure fi,

^ Figure 9'is a diagrammatic view showing the f 7 Claims. (Cl'. 'I4-144) in f '2 angle between theinnei surfaceof'the clutc Ybarrel and thegripping-surface of the clutch block is substantially 'equal foreachincremen't of rotation of thev clutch' barrel, n

Figure 10 isa diagrammatic view showing the shifting ofthe setting of'theclutch barrel'from zero where the inner surface of the clutch barrelis concentric tothe axis'of the actuated shaft to maximum eccentricity'of the clutch barrel relative to the axis of said shaft. f

While the clutch mechanism embodying the improvements' may be used formany purposes, it is particularly'designed Afor use in connection withthe feeding mechanis'mfo'fasewingmachine whereinI the fabric# is'advanced to the stitching mechanism :by 'an'in'termittently rotatedpart. The machinefillustratedin the drawings is a cup feed machine ofthe type shown in the patent granted'EdgarSchoij October 10, 1944, No.2,360,075. Briefly, the machine` includes a 'housing orv frame IinWhichis mounted the main 'actuating shaft`2; -`Said housing is providedwith an overhanging portion 3xsupporting: an inner feed cup 4 andanouter feedv cup 5 between which the fabric; sections are gripped and fedthrough the stitching -mechanism. The stitch ing' mechanismv includes aneedlev' which is'Y 'carriedby a needlefbarreciprocated bysuitablemechanism `from-the main vshaft 2. 'Cooperating with the needlei Iis athread {carrying looper'I which moves into the needle threa'df loop atone *sideA of the'fabric and' then `positions' itself at the other side'off1'the"-fabric.V The looperis carried byafsupporting bar-Which isactuated by suitablemechanism from the-main shaft 2. Cooperating withtheloopen'l is a loop carrier or spreader 8 which engagesr the-looperthread loop and positions it for' theneedle to enter prior topenetrating the fabric sections. This spreader 8l is carried byaspreader bar which is actuated by suitable mechanism lfrom thev mainshaft 2.

The feed cup 4 is carried by a shaft!) mounted for rotation in a sleeveI0 which in turn is fixed to the frame lofthe machine. -The feed cup 5is carried by a shaft-II which is connected through a universal'jointwith a'shaft I2 mounted in a suitable bearing inV the `-overhanging arm3. At the upper end of the shaft 9 there is a -gear wheel I3'carried-'by 'ahub I4 which is secured to a flat section I5y ontheactuated shaft by means of a set screw I6.` Thegear I3 meshes with agearI1 on the shaft I2v and thusrotationsv imparted to the shaft '9arealsof-impalrted'to the'shaft II; thereby the feed cups are operatedin unison and ,turned incrementi'byf'increment for'feeding the fabric tothe stitching mechanism. Therpurpose parts, one of which is theactuating part for turn- Y ing the shaft 9, and the other is the holding'or braking clutch for holding the shaft when turned moved in aclockwise direction and releasing the to a set position and preventingretrograded.

movements thereof as the actuating clutch is returned for a new grip.YThese atwo parts :are simi# lar in construction and a detaileddescrtptioniof one will answer for the other. The clutch mechanismincludes a sleeve I8 to whichtheclutch -bar. Y

rel I9 of the actuating clutch part is integrally connected. The clutchbarrel 20 of the Vbraking clutch is also integrally connected with thissleeve. n theA actuating isha-ft .9 is fa -fhub -2| .which iscylindrical :buteccentrically set rela-tive 'tothe -axis or eenter'ofthefshaft `9. This hub vis provided with a flat portionA 22 vandthesleeve i8 .-isfsecuredto this .fiat portionby arsetA screw 23. Asshownin Figure -8 ,:there:are three 4set screws, one of 4which is' indicatedat: 23;', another at 24, and another-at 25.. By loosening the setscrews, the sleeve may be adjusted on this eccentric ihub so as toposition any one of the three set screws directly over theflat section.isfor the pur- :pose of 'changing `theeccentric#setting of theclutchbarrels' on thek shaft y9,1'as ywill be more fully Aexplainedhereinafter:

Mounted 'for free .rotation chitchplatea; This clutchplatefcarrieson'its runder `face fa clutch block E26. The :clutch block :2Eistrigidlyisecuredto the clutch plate by suita- Y lls'ilezscrews 21;'Therclutch barrel t9. projects -upwardly :fromfthe sleeve I 8 fand Vthelc'lu'tcl'i'blocl':

entends l'doxmmzaitdly ,from the 'clutch iplate i25a and thevouterrfacefofthe clutch block isiopposed to 'the :innery vface sof themclutch barrel. The vclutch block has :three :wedging "faces which vareall similar Vin shape and :are:numberedV28;` 'Dis- 1 posed between eachoperating face' ofthe clutch Y hlockand the inner surface.29ffof1theclutdh barrel i9 lis 1a roller30. 'Thecperating surfaces .of

' the clutch block 2282 are eccentric 'to the inner surface of theclutchbarrel 'and `the roIlersare -fso `dirnensioned Athat they lwill''be-ffrictionally' :gripped by theV l'clutchblock :and `pressed *intofrictional gripping engagement 'with the inner face of the :carrying albamlfstud -341to' whicha `link 35 is con- .nected .This'lli'nk 5351'sconnectedlatits'othervend :to aslotted 'arm-fmounted on arenariaY 31AThe carries .-anarm :38 '.to'which isrionnected Yan eccentric'- strap-'9 cooperating :with an i eccentric 4U zionntlre 4'main :shaft': ias #the:main shaft lrotates ithisneccentr'ic,,will-:through the v'train of tmechanism' iustrlescribed :impart' oscillations to e clutchpIateiandmSther'lutch blockfmoves first I oneV ,aimee-tion` :and `thenthe other; :gripping .the rollers 4to anovefhe-:clutchcharrel whenrollers so that the clutch block can be returned by a counter-clockwisemovement to obtain a new clutch grip on the clutch barrel.

The clutching mechanism which serves to hold the shaft I9 in a setposition is similar to the clutch mechanism for actuating the lshaftexcept that the clutch block 4IV is i'lxed to the sleeve l0 which inturn is fixed to the frame and held from :mo-vement. This clutch block4| has the similarly shaped clutching faces 42 which engage rollers '43`and force the same into gripping contact with the clutch barrel 29. Theclutch barrel will be turned by. the actuating clutch block through `agiven increment of movement and,

when the Lactuating clutch block is turned in the opposite direction fora new gripping connection withthe barrel I9, this barrel 20 will wedgethe roller against the stationary clutch block 4l and prevent anyturning of the shaft 9 in a reverse direction. Associated withtherollers 43 'are compression springs 44 mounted on studs car- Vriedy'by pests L15 'which are rigidly ati'laclfiedk tothe sleeve i@ andtherefore these posts and springs are Vstationary the same as theclut'cl'i.y block 4I.

The .clutch .plate 25a is provided with an annular groove or channel 46inthe upper face thereof. Oil may be supplied to this channel throughopenings 41' in the gear I3. There are cil holes 48 through the clutchplate 25a which are disposed between the posts 32 and the Arollers Yforreciprocating .the clutch.

, In the operation -o-f Ithe Yactuatingclutchl the roller is gripped'between the clutch block. and the inner `:surface A29 of Vthe clutchbarrel. :If-the gripping line ofthe roller Withrthe clutch block werealways in the same position, the clutch block would Wear rapidly,forming a pocket which would soon rpermit the clutch to slip. One of thepurposes of the invention is to provide 'a construction wherein the lineof-grip betweenfthe roller and the clutch block shifts foreach'increment ofmovement of the clutch barrel. Thisshifting `of' thegripping line -of the'v clutch roller with the clutch block isaccomplished by the eccentric setting of the clutch barrel. Y

As has already been noted, `the'outersurfa'ce of Ithe hub '2| Viseccentric to the center of the shaft. Thecenter of `the inner surface of'the' clutch barrel is also eccentric to the center of the hub.

Referring to Figure .10, the circle indicated at Xis the circumferenceof the shaft Yand the center of the :shaft is ,indicated at 'cs'. The.circle Z indicates the circumference vof the .hub and the ,center of thehub as shown in this View it at ch. The center of the inner surface ofthe clutch barrel, which is not indicated in this view, t' is shown `atcb. When the centers cs, ch and Vcb are in alignment, then'the clutchbarrel is at its vmaximum eccentricity. In the preferred setting ofthese centers, the distance from the center of the shaft to the centerof the hub vis .005 'inch andthe distance from the center of the hub tothe center 'ofi the barrel is .005inch so that when the centers are inthe position shown in this diagram, the eccentricity of the barrel lis.O10 vinch from the center of the shaft. The set screw'25 is shown onthis diagram and lindicates ythe setting of the clutch barrel on the hubwhen the flat on the hub hasibeen brought opposite the set screw 25. Atthis setting, the eccentricity of the clutch ,bar-i rel is as noted .010inch. Byloosening the. set screw 25, 'the clutch barrel can .be shiftedon the hub so as to bring the set screw ..24 -oppositefthe :dat Thisanglefofshift is abouto degrees .and

when the set screw 24 is turned up against the -rel is .00'7 inch. Againby loosening the Vscrew 24 the barrel can be shifted about the hub untilthe flat is brought opposite the set screw 23, This shifting is throughan angle of about'130 and when the set screw 23 is set up against theflat, then the eccentricity of the clutch barrel is .004 inch. Thecenter of the clutch barrel as it is shifted about the hub moves inthecircle indicated at Y and at one time it passes through the center ofthe shaft so that the eccentricity of the clutch barrel then is zero. Inother words, the clutch barrel is concentric to the center of the shaft.

The set screws may beaccessible-by removing Vthe cap plate of themachine, but prefereably the vhousing has an opening 49 at the-frontthereof.

Opposite the set screw is an indexing numeral 4 (see Fig. 3) and thisindicates that when the flat on the hub is opposite the set screw23,*the eccentricity of the clutch barrel is .004 inch. A

like indexing numeral 1 is applied to the outer face of the clutchbarrel oppositey the set screw ',ing of the feed cup prevents the flatfrom shifting.

The set screw 24 is then tightened. lThe other` set screw may also betightened against the hub to aid in holding the clutch drum in a setposition on the hub. In like manner, the'eccentrivcity may be furtheradjusted by shifting the clutch drum to bring the set screwv 25 oppositeYthe at. It is noted that the flatr l5 at thev upper end of the shaft,the flat 22 on the hub, and the flat 4a which is contacted with by a setscrew 4b to lock the feed cup -to the shaft are all in alignment. Thisgreatly facilitates the assembling o'f the parts.

There is shown diagrammatically in Figure 9 the inner surface of 'theclutch barrel,Y a'clutch block and one of the rollers. The clutch barrelis set eccentrically to the center of the shaft and :therefore thecenter of the clutch barrel will move in the circular path cb. In thisview, the position of the gripping surface of the clutch barrel when`'the maximum Aeccentricitycis at the upper side of -the figure isindicated by the circle 29a.

The gripping surface of the clutch barrel when the eccentricity is downis indicated'at 29h. The position of the roller when the eccentricity isup is indicated at 3l)a and itv will Ygrip the surface 2i)a of theclutch barrel at S and the clutch block at A. When the eccentricity isdown, then the roller shifts to the position 39h so that it grips theclutch barrel surface 2lib at S and the clutch block at A'. It is notedthat the line of grip `of the roller and the clutch block shifts from Ato A' during the rotation ofthe 'clutch barrel through 180 degrees andthrough the next rotation of y180 degrees the line of grip will shiftback `from A to A.

,of the surface is to'provide a substantially conv 'and the clutchbarrel shifted until the screw 24 is 6 stant wedge angle for allpositions in which the roller is gripped by the` clutch block. The wedgeangle is the angle between a line tangent to the roller at the point ofcontact S` between'the roller and the clutch barrel and a line tangentto the roller at the point .of contact A ofthe roller with the curvedsurface 28. A wedge angle is selected with the clutch barrel at maximumec'- centricity and the roller at the position 30a, which wedge anglewill prevent slippage, and the curvature of the clutch block face is soshaped that the wedge angles for each gripping position 'of the rolleras it shifts back and 'forth on the face of the clutch-block will besubstantially equal regardless of where the gripping of the roller bythe clutch blockv occurs.' The center of the curved surface 28 isdetermined bydropping a line from the center O 'of the roller throughthe point of contact A, and where this lineintersects a line drawn atright angles thereto and passing through the center Cof the shaftdetermines the center'ofthe curved surface of the block. This center isindicated at D. The angle between O-D and O'-C equals the wedge anglefor the roller in the position 3i)a and likewise the angle between O1'Dand O'-C equals the wedge angle for the roller at the position 30h.These wedge angles are substantially equal and likewise the wedgesangles for all gripping points are substantially equal. With thisshifting of the gripping line back and forth foreach rotation of theclutch barrel and with the wedge angles substantially yequal at allportion-s of grip, the life of the clutch is greatly increased beforethe wear on the clutch block` will be suiiicient so as to change anyofthe wedge angles to produce slipping.

The machine is equipped as above noted with Vmeans whereby the eccentricsetting of the clutch barrel may be varied by loosening the screwssecuring the clutch barrel to the hub and shifting the same on theeccentrichub. The machine is preferably adjusted at the factory so thatthe Screw 23 is in contact with the flat and this pro- 'vides for aneccentricity o'f .004 inch. -When the machine has been operated for sometime and wear occurs, then the set screw 23 is loosened opposite theflat. This increases the eccentricity of the setting of the clutchbarrel and it will alsoincrease the distance between A and A', vthelimits ofthe area where the roller grips the clutch block, and bring newsurfaces into contact with the roller. Then again, when wear isapparent, the set screw 24 can be loosened and the screw 25 broughtopposite the flat and this will increase the eccentricity of .010 inchand it will also further increase the distance from A to A over whichthe line of contact between the roller and the clutch block shifts. Bythese three settings, the area of the line of contact is increased fromthe original setting and thus the wear and life of the clutch areprolonged. Regardless of the eccentricity of the clutch barrel, thewedge angles for all setting will be substantially constant. This notonly permits a greater range of adjustment of theeccentricity, but italso prolonge the life of the clutch before wear can possibly change thewedge angle sufficiently to bring about slippage.

Let us assume that the machine is set for producing ten stitches to theinch and that the inner circumference of the clutch barrel is fiveinches. Then for each rotation of the clutch barrel there would 'be ftyYincrements of movement of the clutch'barrelf" While moving the clutchbarrel'through.18.0.Jdegrees there. `would `be twentyeve increments-ofmovement, Let-us 4assume that the .distance fronilA--A is at a maximumbecause ofthe setting of the clutch 'barrel' vat a maximum -eccentricityEach increment iof movement` alongxthis line A-A would ybe 1,55the'distance.` If' thezeccentricity Iof vthe `clutch barrel is shiftedsofas to shorten the line A-A still the increments of movement would beof whateverY the distance is and therefore the distance between .thevlines of' Contact for one setting will be different 'than the distancebetween thelines-of lContact for. another setting of theeccentriciiw ofthe. clutch barrel. '.ituthier Yaids inthe distnihutionfof the wear aonthe'surface fromA-LAC f i This construction vof clutchv wherein theVwedge -angieis maintainedsub'stantially constant .for all 'points of-grip accomplishes twoY distinct advantages in the voperation of4 aneccentric-ally set clutch barrel." One, it enab-l'es'the wedge angl/e tobe selected which willgive a long'lfe tov the crutch before. the Wearon'the clutching face `of the clutch block will be .sufficient toproduce:

`this constant wedge angle clutch Vall three rollers 1 may have the sameWedge. angle and 'therelore each roller will carry about the :sameamount of lead .which'rerluces the wear rate.

Vinstead of the rollersV .ballsv might .be used. Itis preferred,however, ato use. rollers,as the-contact between the rollers. and thepartssd'irectly This rclutch block .being curved soithat the wedge angleis substantially constant for all gripping positions` of the rollers.'

vrassociated therewthis a line contact instead of Y a pointcontact.While the :clutch has been "described :in detail inconnection with afeed cup type ofV machine, it will `nowzloe understood that theclutchmay be -used for'imparting intermittent movementr toa `rot-arypart in other typesfof Y feeding mechanisms andralso Vin other types =ofmachines. i

lt will alsobe Vobvious that minor Ichanges .in

the details of construction may be made without departing from thespiritof the invention asset forth in the appendedv claims; f

' I claim: Y

' 51. A 4v@hitchnieclfianism for sewing machines x comprising anactuatedshaft, a clutch barrel on said shaft, a clutch block-'associatedwith said barrel, gripping rollers between the clutch block positions ofthe rollers.

Seurin'Nv er 2. A clutch mechanismfor 4comprising an :actuated .fshafaahub on Asaid shaft, vthe center of which 'is eccentric "to :the

rs1/raft, a .sleeve .mounted zonxsaid hub, a clutch .barrel ionsaidsleeve; said clutch barrel ibeing eccentric 'to '.tli'eefcenter ofthe E1hub,f2a .clutch block 3. A .clutch mechanism for sewing machinescomprising `an Aactuated: shaft, a `hub on .said shaft, thecenterofrwhfic'h' is -eccentricto the center of the shaft, a sleeve on saidhub, a driving clutch barrel and a Abraking.clutch barrel carried. bysaid. sleeve, the clutching surface of each barrel being eccentricftothe center of the hub, a clutch block associated with each barrel, meansfor holding one of :said: clutch blocks stationary, 'and means `foractuating the other clutch block, :rollers associated with 'each'-clutch 'block for gripping the clutch barrelsgand' a compression tendingto 'holdV the rollerir-rclutchin'g engagement withthe clutch blocksandclutch barrels,

the clutching faces of' :each Aclutch block being curved so: that thewedge .angle is substantially 'constant for all. lpositionsvof the:rollers.

4. A clutch Irneclflanismy for'iseWi-ng.' machines comprising anactuated shaft', a hubron' 'said shaft, the center .of which is.eccentricv tofthe center` of the shaft, y`a :sleeve `on `said hub',.adrivving l'clutch' barrel.V and Aa braking vclutch .barrel carried' bysaid sleeve, the clutching surface of each barrel being/'eccentric tothe center l'oi-the hub, a clutch block vassociated with reach barrel,means for holding one .of'said clutchblo'clrs stationary and :means foractuating the other clutch block, rollers associated with each clutchblock 'for gripping the. clutch barrels, a .compression springassociatedwith each-roller and normally `.tending to Vhold' the rollerin clutching engagementwiththe. clutch blocks andclutch barrels,

.the'clutching surfaces offthe clutch .blocks being curved so .that thewedge fangle. is vsubstantially constant for all gripping.'pos`itionsof' the rollers.v

5. A .clutch- :mechanism 4for sewing machines v'comprising an actuatedy.Shar-t,V a hub on said shat, .thecenter of Vwhich 'is' .eccentric tothe cen- Vrter of thefshart; a clutch "barrel mounted on said hub, thecenter of .the- `clutch barrel v.being eccentric to the center .of `thehubya clutch block as.- sociated with said barrel, .gripping rollers.'between ftheclutch block 'and said barrel, Vmeans for oscillating theclutch-block'for moving the .barrel intermittently', vandmeans wherebysaid clutch 'harrel-v may .be shifted fonsaifd :hub to. :different setpositionsriforvarying'the eccentricity ofthe clutch "65 barrel relative`to .the center of the shaft.

6. A. clutch `mechanism'.forsewing machines comprising anactuatedlshaft'a hub onv said-shaft,

`the center 'ofiwlichis :eccentric to. the 'center of the .'s'hat,'said' "hub .having .a :flat on one side .thereo'afsle'eve 'mounted'on'fsaid hub, ya clutch barrel carried by sa-id sleeve, the center ofthe clutch barrel being eccentric 'to the center of thehub, a 'clutchblock associated 'with said bar- :relgfgripping'rollersbetween theyclutch 'block :and said barrel', 'means .iforloscilifatingtheclutch'blcck for moving said barrel intermittently, said sleeve havingset screws extending therethrough at different radial points whereby aselected set screw may be positioned in radial alignment with the flatfor securing the sleeve to the hub and by shifting from one set screw toanother the eccentricity of the clutch barrel may be varied, and meansassociated with each set screw for indicating the eccentric setting ofthe clutch barrel.

7. A clutch mechanism for sewing machines comprising an actuated shaft,a hub on said shaft, the center of which is eccentric to the center ofthe shaft, a clutch barrel mounted on said hub, the center of the clutchbarrel being eccentric to the center of the hub, a clutch blockassociated with said barrel, gripping rollers between the clutch blockand said barrel, the clutching faces of each clutch block being curvedso that the wedge angle is substantially constant for all positions ofthe rollers, means for oscillating the clutch block for moving thebarrel intermittently,

10 and means whereby said clutch barrel may be shifted on said hub todifferent set positions for Varying the eccentricity of the clutchbarrel relative to the center of the shaft.

EDGAR SCHOIJ.

REFERENCES CITED The following references are of record in the le ofthis partent:

UNITED STATES PATENTS

